April 11, 2011

The rainfall in Andhra Pradesh is influenced by both South-West and North-East monsoons. Of the normal annual rainfall of 940 mm, 624 mm (66%) is contributed by South-West Monsoon (June-September) followed by 224 mm (24%) during the North-East Monsoon (October-December) and 10% during the Winter and Summer months.

Region wiseRainfall (in mm) During South West Monsoon -2010

Sl.

No.

Region

01.06.2010 – 30.09.2010

Status

Normal

Actual

Dev

(%)

1

Coastal Andhra

620

868

(+)40

Excess

2

Rayalaseema

407

529

(+)30

Excess

3

Telangana

715

892

(+)25

Excess

State

624

808

(+)29

Excess

The normal annual rainfall of the State is 940 m.m. Major portion (66%) of rainfall is contributed by South-West Monsoon (June-Sept) followed by (24%) North-East Monsoon (Oct-Dec). The rest 10% of the rainfall is received during the winter and summer months.

The Normal rainfall distribution in the three regions of the State differs with the season and Monsoon. The influence of South-West Monsoon is predominant in Telangana region (716m.m) followed by Coastal Andhra (620 m.m) and Rayalaseema (407 m.m), whereas the North-East Monsoon provides high amount of rainfall in Coastal Andhra area (324 m.m) followed by Rayalaseema (238 m.m) and Telangana (129 m.m). There are no significant differences in Normal distribution of rainfall during winter and hot weather periods among three regions

S.No

YEAR

South-West Monsoon

North-East Monsoon including Winter and Hot Weather period

Total Rainfall (in mm)

Normal

Actual

% dev

Normal

Actual

% dev

Normal

Actual

% dev

1

1966-67

600

643

7

290

305

5

891

947

6

2

1976-77

602

673

-12

293

352

20

895

1025

15

3

1986-87

602

597

-1

294

271

-8

896

868

-3

4

1996-97

634

737

16

291

373

28

925

1109

20

5

2005-06

624

690

11

316

457

45

940

1147

22

6

2006-07

624

627

0.5

316

231

-27

940

858

-9

7

2007-08

624

747

+20

316

333

+5

940

1080

+15

8

2008-09(*)

624

666

+7

274

149

-45

898

815

-9

(*) (from 1.6.08 to 1.4.09)

According to data provided by the Indian Metrological Department (IMD) to the State, traditionally drought-prone part of Rayalaseema has recorded 52 per cent excess rain (236.6 mm as against normal of 155.5 mm) and Coastal Andhra region received 48 per cent excess rain (375.2 mm as against the normal rainfall of 253.9 mm). The Telangana region, including the twin cities of Hyderabad and Secunderabad, has received about 10 per cent excess rain (361.9 mm as against 327.8 mm).

Studies made by Hydrological Project Circle, Hyderabad, Guntur Division have found that quantum of summer monsoon rainfall in the district has been steadily increasing in the last decade which could lead to severe imbalances in the rainfall distribution resulting in extremities like flash floods or severe drought conditions.

There will be no change in the average quantum of rainfall in the country. But, significant changes in rainfall recorded region-wise are likely. For instance, if June received good rains, July might see a dull monsoon and if August sees a good monsoon, September might go dry.

The farmers should be educated on these aspects in advance so that they could change their sowing pattern accordingly.

The most significant changes could be intensity and rise in frequency of tropical cyclones, rise in frequency of low pressure depressions intensifying and turning into cyclones and a rise in maximum temperature across the country. The data revealed that summer temperatures in the country over the past 100 years had showed an increase between 0.6 degree and one degree Celsius.